Method for producing a synthesis gas

ABSTRACT

A method and system are provided for feeding a biomass material feed into a fluidized bed gasifier. The system includes a first plurality of screw conveyors disposed circumferentially around and connected to or integral with a gasifier shell of the fluidized bed gasifier, such that each of the first plurality of screw conveyors is in feed communication with a gasifier chamber defined by the gasifier shell. The system also includes a plurality of secondary receptacles, each individually coupled to a respective screw conveyor of the first plurality of screw conveyors, such that each of the plurality of secondary receptacles includes a secondary receptacle shell defining a secondary receptacle chamber in feed communication with the respective screw conveyor. The system further includes a plurality of primary receptacles, each including a primary receptacle shell defining a primary receptacle chamber in feed communication with at least two of the plurality of secondary receptacles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/898,838, filed on May 21, 2013, which claims priority to EuropeanPatent Application Serial No. 12382203.3, which was filed May 24, 2012.These priority applications are hereby incorporated by reference intheir entirety into the present application to the extent consistentwith the present application.

BACKGROUND

Hydrocarbons are a major source of energy for much of the world's energyneeds. Recent cost increases in hydrocarbon-based fuels, induced in partby increased demand for hydrocarbons from developing countries andconcerns of supply shortages due to the increased demand, has generatedincreased interest in finding alternative sources of energy for theworld's needs. In researching alternative energy sources, focus has beendirected to those energy sources meeting at least the criteria of beinginexpensive, renewable, and plentiful.

One such alternative energy source capable of meeting the aforementionedcriteria has been developed from biological waste products. Biologicalwaste products are a desirable energy source due to the prevalence ofsuch products, and the accompanying need to dispose of these products inan environmentally prudent manner. Such biological waste products aregenerally referred to as biomass and may include agricultural and othercellulosic waste materials. Nonlimiting examples of biomass may includeforest residues, agricultural residues, nuts, nut shells, wood chips,olive and grape mash, and urban biomass, such as municipal solid waste.

Biomass may be converted into a useful gas mixture through a process ofgasification. Generally, gasification is a process that converts atleast a portion of the biomass material into a useful gas mixture,commonly referred to as synthesis gas (or syngas), through the reactionof the biomass material at high temperatures (>700° C.) with acontrolled amount of oxygen and/or steam. Synthesis gas is combustibleand may be utilized, for example, as a fuel gas in gas and steam boilerplants, as an intermediate in generating synthesis natural gas, or forthe production of other chemicals, such as methanol.

The gasification process may be carried out at least in part in agasification unit, commonly referred to as a gasifier. The gasifier maybe, for example, a counter-current fixed bed gasifier, a co-currentfixed bed gasifier, a fluidized bed gasifier, an entrained flowgasifier, or a plasma gasifier. The type of gasifier utilized may bebased in part on particular technological and/or commercial needs orfactors. For instance, the fluidized bed gasifier may be very useful forfeed fuels forming highly corrosive ash due to the propensity of suchash to damage the walls of other gasifiers. Because biomass material isa feed fuel that generally contains high levels of corrosive ash, afluidized bed gasifier may be often utilized for converting biomass feedmaterial to synthesis gas through the process of gasification.

Typically, the biomass material is fed to the fluidized bed gasifierthrough a single inlet defined by the fluidized bed gasifier. In feedingthe biomass material into the fluidized bed gasifier through the singleinlet, the reaction in the gasifier may occur in only a portion of thegasifier causing undesirable pressure and temperature differentials inthe gasifier. Such a pressure and temperature differential may result ina portion of the biomass material exiting the gasifier unreacted, thusresulting in lower process efficiency.

What is needed, then, is a system for feeding biomass material into afluidized bed gasifier such that the homogeneity of pressure andtemperature in the reactor is increased, thereby resulting in animprovement in the conversion of biomass material to synthesis gas andincreased process efficiency.

SUMMARY

Embodiments of the disclosure may provide a system for feeding a biomassmaterial feed into a fluidized bed gasifier. The system includes a firstplurality of screw conveyors disposed circumferentially around andconnected to or integral with a gasifier shell of the fluidized bedgasifier, such that each of the first plurality of screw conveyors is infeed communication with a gasifier chamber defined by the gasifiershell. The system also includes a plurality of secondary receptacles,each individually coupled to a respective screw conveyor of the firstplurality of screw conveyors, such that each of the plurality ofsecondary receptacles includes a secondary receptacle shell defining asecondary receptacle chamber in feed communication with the respectivescrew conveyor. The system further includes a plurality of primaryreceptacles, each including a primary receptacle shell defining aprimary receptacle chamber in feed communication with at least two ofthe plurality of secondary receptacles.

Embodiments of the disclosure may further provide a system for producinga synthesis gas from a biomass material feed in a fluidized bedgasifier. The system includes a first plurality of screw conveyors, eachdisposed equidistantly from an adjacent one of the first plurality ofscrew conveyors and circumferentially around and connected to orintegral with a gasifier shell of the fluidized bed gasifier, such thateach of the first plurality of screw conveyors is in feed communicationwith a gasifier chamber defined by the gasifier shell. The system alsoincludes a plurality of secondary hoppers each coupled to respective oneof the first plurality of screw conveyors and further configured toprovide a continuous feed of the biomass material feed to the respectiveone of the first plurality of screw conveyors. The system furtherincludes at least one primary hopper configured to provide each of theplurality of secondary hoppers with the continuous feed of the biomassmaterial feed.

Embodiments of the disclosure may further provide a method for producinga synthesis gas from a biomass material feed in a fluidized bedgasifier. The method includes feeding the biomass material feed into abiomass feed system including a plurality of screw conveyors, eachdisposed equidistantly from an adjacent one of the plurality of screwconveyors and circumferentially around and connected to or integral witha gasifier shell of the fluidized bed gasifier, such that asubstantially equal amount of the biomass feed material flows througheach of the plurality of screw conveyors into the gasifier chamber. Themethod also includes feeding a fluid flow into a bottom section of thegasifier chamber of the fluidized bed gasifier, such that the fluid flowand the biomass material feed contact and react to form the synthesisgas.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying Figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale. In fact, the dimensions of the variousfeatures may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a top plan view of a biomass feed system, accordingto an embodiment.

FIG. 2 illustrates a side elevation view of a section of the biomassfeed system including a primary receptacle and a secondary receptacle,according to an embodiment.

FIG. 3 illustrates a cross-sectional view of a section of the biomassfeed system including a secondary receptacle and a screw conveyor,according to an embodiment.

FIG. 4 illustrates a flowchart of a method for producing synthesis gasfrom a biomass material feed in a fluidized bed gasifier, according toan embodiment.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes severalexemplary embodiments for implementing different features, structures,or functions of the invention. Exemplary embodiments of components,arrangements, and configurations are described below to simplify thepresent disclosure; however, these exemplary embodiments are providedmerely as examples and are not intended to limit the scope of theinvention. Additionally, the present disclosure may repeat referencenumerals and/or letters in the various exemplary embodiments and acrossthe Figures provided herein. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various exemplary embodiments and/or configurationsdiscussed in the various Figures. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact.Finally, the exemplary embodiments presented below may be combined inany combination of ways, i.e., any element from one exemplary embodimentmay be used in any other exemplary embodiment, without departing fromthe scope of the disclosure.

Additionally, certain terms are used throughout the followingdescription and claims to refer to particular components. As one skilledin the art will appreciate, various entities may refer to the samecomponent by different names, and as such, the naming convention for theelements described herein is not intended to limit the scope of theinvention, unless otherwise specifically defined herein. Further, thenaming convention used herein is not intended to distinguish betweencomponents that differ in name but not function. Additionally, in thefollowing discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to.” All numericalvalues in this disclosure may be exact or approximate values unlessotherwise specifically stated. Accordingly, various embodiments of thedisclosure may deviate from the numbers, values, and ranges disclosedherein without departing from the intended scope. Furthermore, as it isused in the claims or specification, the term “or” is intended toencompass both exclusive and inclusive cases, i.e., “A or B” is intendedto be synonymous with “at least one of A and B,” unless otherwiseexpressly specified herein.

FIGS. 1-3 illustrate an exemplary biomass feed system 100, according toan embodiment. In an exemplary embodiment, the biomass feed system 100is configured to feed biomass material to a fluidized bed gasifier 102.The biomass material may be a homogeneous biomass material, such thatthe biomass material is formed from a single source. The biomassmaterial may instead be a heterogeneous biomass material, such that thebiomass material is formed from a plurality of sources. The biomassmaterial may include, for example, forest residues, agriculturalresidues, nuts, nut shells including almond shells, wood chips includingpine, eucalyptus, oak, and poplar, olive and grape mash, and rice husks.The biomass material may include low density biomass material generallyhaving a density less than about 250 kg/m³, and in an exemplaryembodiment, having a density less than 150 kg/m³.

The fluidized bed gasifier 102 may include a cylindrical gasifier shell104 defining a gasifier chamber 106, which, as shown in FIG. 3, has atop gasifier chamber section 108 and a bottom gasifier chamber section110. A distributor plate (not shown) may be disposed in the bottomgasifier chamber section 110 and above a gasifier fluid inlet (notshown) defined by a bottom section 112 of the cylindrical gasifier shell104. The gasifier fluid inlet may be configured to feed an oxidant, suchas air or oxygen, and/or steam to the gasifier chamber 106. Thedistributor plate may further define a plurality of plate openings (notshown) configured to provide a fluid passageway through which thegasifier fluid inlet feed may flow. The plate openings may be furtherconfigured to induce turbulence in the gasifier fluid inlet feed flow.

A syngas feed outlet 115 is defined by a top section 114 of thecylindrical gasifier shell and is configured to feed syngas producedfrom the reaction of the biomass material to an external component,e.g., scrubber, for further processing. In another embodiment, thefluidized bed gasifier 102 may include one or more cyclones (not shown)disposed in the top section 108 of the gasifier chamber and in fluidcommunication with the gasifier chamber 106 and the syngas feed outlet115. The cyclone(s) may be configured to separate one or more biomassparticulates of the biomass material feed from the syngas feed, suchthat the syngas feed may flow through the syngas feed outlet 115 and theone or more biomass particulates may be routed to the bottom section 110of the gasifier chamber 106.

The biomass feed system 100 may include one or more primary receptacles,illustrated as a plurality of primary hoppers 116 in FIG. 1. In anexemplary embodiment, the plurality of primary hoppers 116 includes twoprimary hoppers, such that the primary hoppers may be disposed proximateto and circumferentially around the fluidized bed gasifier 102. In anexemplary embodiment, each primary hopper 116 is disposed proximate toan opposing side of the fluidized bed gasifier 102 and is 180 degreesapart from the other primary hopper. However, embodiments in which theprimary hoppers 116 are greater or less than 180 degrees apart arecontemplated herein. Further, additional or fewer primary hoppers 116may be used without departing from the scope of the disclosure.

Each primary hopper 116 may include one or more primary sidewalls 118defining a primary hopper chamber 119. In an exemplary embodiment, theprimary hopper 116 includes four primary sidewalls 118 defining at leastin part the primary hopper chamber 119. The primary sidewalls 118 may beconfigured such that the primary sidewalls 118 further define a primaryhopper top section 121 defining a primary hopper top opening 120 and, inaddition, define at least in part a primary hopper bottom section 123defining a primary hopper bottom opening 122. The primary hopper bottomsection 123 may include a plurality of primary hopper screw conveyors125 proximate to and in feed communication with the bottom sectionopening 123. In an exemplary embodiment, the primary hopper bottomsection 123 may include four primary hopper screw conveyors 125configured in pairs and oriented such that a pair of the primary screwconveyors 125 opposes the other pair of primary screw conveyors 125. Theprimary hopper top opening 120 may be configured to define a largersurface area opening than the primary hopper bottom opening 122, therebyallowing an increased biomass material feed through the primary hoppertop opening 120.

In an exemplary embodiment, the primary hopper 116 may be operativelycoupled to a primary hopper level detector 124. The primary hopper leveldetector 124 may include a sensor, and is configured to detect the levelof biomass material disposed within the primary hopper 116 duringoperation of the biomass feed system 100. The primary hopper leveldetector 124 may be further configured to transmit a signal to acontroller (not shown) when the biomass material disposed within theprimary hopper 116 has reached a predefined level, thereby causingadditional biomass material to be added to the primary hopper 116.Conversely, the primary hopper level detector 124 may be configured totransmit a signal to the controller when the biomass material disposedwithin the primary hopper 116 has reached a predefined level, therebycausing the flow of biomass material to the primary hopper 116 to bediscontinued.

The biomass feed system 100 further includes one or more secondaryreceptacles, illustrated as a plurality of secondary hoppers 126 inFIGS. 1-3, in feed communication with a primary hopper 116. In theexemplary embodiment illustrated in FIG. 1, each of the primary hoppers116 is in feed communication with four secondary hoppers 126. Eachsecondary hopper 126 is disposed about equidistantly from an adjacentsecondary hopper 126 and further disposed proximate to andcircumferentially around the fluidized bed gasifier 102 such that thesecondary hoppers 126 are oriented at angle θ apart from each other inrelation to the center of the fluidized bed gasifier 102. In theillustrated embodiment of FIG. 1, the angle θ is about 45 degrees.Embodiments in which each primary hopper 116 is in feed communicationwith greater or less than four secondary hoppers 126 are contemplatedherein. In such embodiments, each secondary hopper 126 may be disposedequidistantly from an adjacent secondary hopper 126 and further disposedproximate to and circumferentially around the fluidized bed gasifier102. The angle θ may be greater or less than 45 degrees.

Each secondary hopper 126 may include one or more secondary sidewalls128 defining a secondary hopper chamber 130. In an exemplary embodiment,the secondary hopper 126 includes four secondary sidewalls 128 definingthe secondary hopper chamber 130. The secondary sidewalls 128 may beconfigured such that the secondary sidewalls further define a secondaryhopper top opening 132 and a secondary hopper bottom opening 134. Thevolume of the secondary hopper chamber 130 in a top section 136 of thesecondary hopper chamber 130 may be greater than a bottom section 138 ofthe secondary hopper chamber 130, thereby allowing the biomass materialfeed to funnel therethrough.

In an exemplary embodiment, the secondary hopper 126 may be operativelycoupled to a secondary hopper level detector 133. The secondary hopperlevel detector 133 may include a sensor, and is configured to detect thelevel of biomass material disposed within the secondary hopper 126during operation of the biomass feed system 100. The secondary hopperlevel detector 133 may be further configured to transmit a signal to acontroller (not shown) when the biomass material disposed within thesecondary hopper 126 has reached a predefined level, thereby causing adrive motor 146, discussed further below, to cease operation for apredetermined interval of time. The drive motor 146 may resume operationafter the expiration of the predefined time interval.

The biomass feed system 100 may further include a plurality of screwconveyors 140, each configured to receive the biomass material feed froma respective secondary hopper 126. As shown in FIG. 1, the biomass feedsystem 100 may include a screw conveyor 140 in feed communication with acorresponding secondary hopper 126. The fluidized bed gasifier 102 maybe further configured such that the cylindrical gasifier shell 104 maydefine a plurality of screw conveyor openings 142 configured tosealingly connect the screw conveyor 140 and the cylindrical gasifiershell 104 such that the screw conveyor 140 and gasifier chamber 106 arein feed communication. In another embodiment, each screw conveyor 140 isintegral with the cylindrical gasifier shell 104. The screw conveyoropenings 142 are defined equidistantly apart from an adjacent screwconveyor opening 142 such that the screw conveyors 140 are spacedequidistantly apart around the circumference of the bottom section 112of the cylindrical gasifier shell 104. In an exemplary embodiment, eachscrew conveyor 140 is operatively coupled to the drive motor 146. Thedrive motor 146 may be, for example, an electric motor.

The screw conveyor 140 may include a screw conveyor housing 144 defininga screw conveyor chamber 148 as shown most clearly in FIG. 3. The screwconveyor 140 further includes an auger 150 operatively connected to thedrive motor 148 and configured to urge the biomass material disposedtherein toward and into the fluidized bed gasifier 102. The auger mayinclude inox 306 stainless steel material. In an exemplary embodiment,the auger 150 may be a variable-pitch auger. The pitch of the auger 150may decrease along the flow of the biomass material feed. In anotherembodiment, the auger 150 may include a single flight variable pitch. Insome embodiments, the auger 150 may be a double flight standard pitch.Thrust bearings (not shown) may assist in managing thrust that isexerted onto the auger 150. The auger 150 may be further configured toform a seal with the screw conveyor housing 144 and the biomass materialfeed when disposed therein and compressed by the auger, such that syngasformed in the fluidized bed gasifier 102 may not flow through the screwconveyor 140 upstream to the external environment.

Turning to the operation of the biomass feed system 100, an exemplaryoperation of the biomass feed system 100 embodied in FIGS. 1-3 ispresented now. In such an exemplary operation, the biomass material feedmay be fed to the plurality of primary hoppers 116 illustrated in FIG. 1from a single biomass material feed source (not shown). In anotherembodiment, each primary hopper 116 is fed from a separate and distinctbiomass material source. In an exemplary embodiment, biomass materialfeed source provides a continuous biomass material feed to each of theprimary hoppers 116. The primary hoppers 116 may be gravity-fed from thebiomass material feed source.

In an exemplary operation of the biomass feed system 100, the biomassmaterial feed may include low density wood chips formed from, forexample, a poplar tree. However, it will be appreciated by one ofordinary skill in the art that the biomass material feed may be formedfrom one or more heterogeneous or homogeneous biomass materials sources.Nonlimiting examples of biomass material feed sources include forestresidues, agricultural residues, nuts, nut shells including almondshells, wood chips including pine, eucalyptus, oak, and poplar, oliveand grape mash, and rice husks.

Biomass material feed enters the primary hopper 116 through the primaryhopper top opening 120 and flows through each primary hopper 116 in acondensed and uniform manner such that voids or pockets may be eitherprevented from forming or substantially eliminated in the biomassmaterial feed disposed in the primary hopper. Gravity forces the biomassmaterial feed toward the primary hopper bottom section 123 and intocontact with the plurality of primary hopper screw conveyors 125disposed in the primary hopper bottom section 123. In an exemplaryembodiment, the primary hopper bottom section 123 includes four primaryhopper screw conveyors 125. Each of the primary hopper screw conveyors125 disposed in the primary hopper bottom section 123 is in feedcommunication with a respective line 152,154,156,158 such that aconstant feed of biomass material feed contacting each primary hopperscrew conveyor 125 is urged through the primary hopper bottom opening122 and may flow through the respective one of the lines152,154,156,158. In an exemplary embodiment, the biomass feed system 100is configured such that lines 152,154,156,158 are each provided with asubstantially equal flow of the biomass material feed therethrough.

The biomass material feed flowing through each of line 152 and line 154is fed into a respective secondary hopper top opening 132 and into thesecondary hopper chamber 130. The biomass material feed flowing througheach of line 156 and line 158 is further fed through line 160 and line162 respectively and through the respective secondary hopper top opening132 into the secondary hopper chamber 130. In an exemplary embodiment,each of the secondary hoppers 126 may be provided with the biomassmaterial feed having a flow rate substantially similar to the biomassmaterial feed provided to each adjacent secondary hopper 126.

The biomass material feed in each of the secondary hoppers 126 may befed through the bottom opening 134 of the secondary hopper 126 into thescrew conveyor chamber 148 of the screw conveyor 140. A drive motor 146including a speed regulator (not shown) and operatively connected to theauger 150 may continuously drive the auger 150 thereby causing the auger150 to rotate at a speed, for example, of 25 Hz in an exemplaryembodiment. It will be understood by one of ordinary skill in the artthat the rotational speed of the auger 150 may vary based, for example,on the flow rate or the composition of the biomass material feed or thereaction conditions in the fluidized bed gasifier 102. Thus, therotational speed of the augers 150 may be increased to increase the flowof biomass material feed into the fluidized bed gasifier in order toincrease the production of syngas. Conversely, the rotational speed ofthe augers 150 may be decreased to decrease the flow of biomass materialfeed into the fluidized bed gasifier in order to decrease the productionof syngas. In an exemplary embodiment, the rotational speed of eachauger 150 in the biomass feed system 100 may be substantially equal.

As the biomass material feed is fed into the screw conveyor chamber 148,the auger 150 conveys the biomass material feed into the gasifierchamber 106. The biomass material feed is conveyed by the auger 150 suchthat the auger, screw conveyor housing 144, and biomass material feedform a sealing relationship so that syngas produced in the fluidized bedgasifier 102 may be prevented from flowing back through the screwconveyor housing 144 and upstream of the secondary hopper 126 to theexternal environment.

In an exemplary embodiment, air is fed from a feed fluid source (notshown) into the gasifier chamber 106 via the gasifier fluid inlet. Theair feed contacts the distributor plate disposed in the bottom section110 of the gasifier chamber, such that the air feed is forced through aplurality of plate openings defined in the distributor plate andconfigured to induce turbulence in the air feed flow. In addition, afluidifying agent, e.g., dolomite (having a diameter of 1 mm), may bedisposed in the fluidized bed gasifier 102. The biomass material feedmay be fed from each screw conveyor 140 into the fluidized bed gasifier102 at a substantially equal flow rate, and further may contact theturbulent air/dolomite feed thereby reacting to form syngas. Theequidistant spacing of the screw conveyors 140 circumferentially aroundthe fluidized bed gasifier 102 and the substantially equal flow rate ofthe biomass material feed fed through each screw conveyor provides forthe biomass material feed to react with the oxygen feed in the fluidizedbed gasifier 102 such that the pressure and temperature in a section ofthe gasifier chamber 106 proximate to a screw conveyor 140 issubstantially similar to the temperature and pressure of an adjacentsection including an adjacent screw conveyor 140. Such homogeneouspressure and temperature conditions provide for increased efficiency ofthe conversion of the biomass material feed to syngas.

In an exemplary embodiment, the biomass feed system 100 may be acontinuously-run system. The mass flow rate of the biomass material feedentering each primary hopper 116 may determine the flow rate of syngasflowing from the fluidized bed gasifier 102 in at least one embodiment.The mass flow rate of the biomass feed material entering each primaryhopper 116 may determine the rotational speed of the auger 150 disposedin the screw conveyor 140 in an exemplary embodiment.

FIG. 4 illustrates a flowchart of an exemplary method 200 for producingsynthesis gas from a biomass material feed in a fluidized bed gasifier,according to an embodiment. The method 200 includes feeding the biomassmaterial feed into a biomass feed system including a plurality of screwconveyors, as at 202. Each of the plurality of screw conveyors may bedisposed equidistantly from an adjacent one of the plurality of screwconveyors and circumferentially around and connected to or integral withthe gasifier shell of the fluidized bed gasifier. A substantially equalamount of the biomass feed material may flow through each of theplurality of screw conveyors into the gasifier chamber. A fluid flow maybe fed into a bottom section of the gasifier chamber of the fluidizedbed gasifier, in which the fluid flow and the biomass material feed maycontact and react to form synthesis gas, as at 204.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the present disclosure. Thoseskilled in the art should appreciate that they may readily use thepresent disclosure as a basis for designing or modifying other processesand structures for carrying out the same purposes and/or achieving thesame advantages of the embodiments introduced herein. Those skilled inthe art should also realize that such equivalent constructions do notdepart from the spirit and scope of the present disclosure, and thatthey may make various changes, substitutions and alterations hereinwithout departing from the spirit and scope of the present disclosure.

I claim:
 1. A method for producing a synthesis gas from a biomassmaterial feed in a fluidized bed gasifier, comprising: feeding thebiomass material feed from at least one biomass material feed source toa plurality of primary hoppers, each primary hopper in feedcommunication with at least two secondary hoppers of a plurality ofsecondary hoppers, wherein each secondary hopper is in feedcommunication with only one primary hopper; feeding the biomass materialfeed from each primary hopper to the respective at least two secondaryhoppers; feeding the biomass material feed from each secondary hopper toa respective screw conveyor of a plurality of screw conveyors, eachscrew conveyor disposed equidistantly from an adjacent one of theplurality of screw conveyors and circumferentially around and connectedto or integral with a gasifier shell of the fluidized bed gasifier,wherein a substantially equal amount of the biomass feed material flowsthrough each of the plurality of screw conveyors into a gasifier chamberdefined by the gasifier shell; and feeding a fluid flow into a bottomsection of the gasifier chamber of the fluidized bed gasifier, whereinthe fluid flow and the biomass material feed contact and react to formthe synthesis gas.
 2. The method of claim 1, wherein the fluid flowcomprises oxygen.
 3. The method of claim 1, wherein at least one screwconveyor of the plurality of screw conveyors comprises a screw conveyorhousing and an auger disposed within the screw conveyor housing, theauger being operatively coupled to a drive motor, wherein the screwconveyor housing and the auger are configured to form a sealingrelationship with the biomass material feed disposed therein such thatthe synthesis gas formed from a reaction of the biomass material feed isprevented from flowing upstream of the screw conveyor.
 4. The method ofclaim 1, further comprising rotating the biomass material feed in atleast one primary hopper in feed communication with the plurality ofscrew conveyors, such that one or more voids are prevented from formingin the biomass material feed.